noob from the MS coast

hey! I found this forum thanks to google and found so much awesome information I had to join.
I currently have 9 chicks in a brooder in my kitchen LOL 3 australorp, 3 barred rock, 3 white rock or white leghorn, they are a bit of a mystery. I also have one chick in a sick bay, she's a red pullet from tractor supply. That's where I work. I've brought home 6 chicks that have been sick and she's the only one left. I also have 3 dogs, 2 cats, 2 guinea pigs, a ferret, and a horse, 3 kids, and a husband in the Navy. it's a full house and it's always an adventure around here.
Hoping to finish up the coop over the next couple of weeks. I decided on an A frame design with one end dedicated to the coop instead of the entire top half. Trying my hardest to make it as predator resistant as possible and still have good air flow since mississippi summers can be brutal. right now the total area is 8 ft wide and 12 ft long and the coop is double decker and I'm still working out the kinks. my chicks are only about 3 weeks old so we still have time to get it done.
I look forward to learning more as time goes on!

The sick chicks are kept away from the healthy ones. They've never been in contact at all. I'm an obsessive hand washer and water changer and poop scooper. Thanks for all the welcomes! This isn't my first time with chickens, but it has been awhile.

What is wrong with this sick chick? What symptoms does she have? You might want to keep this one warmer than the other brooders temp. Sick birds need more heat than healthy ones. If the chick is not eating well, feed the baby some crushed up hard boiled eggs. Eggs are good emergency food for birds and sick birds tend to not want to eat their starter feed. So to keep the bird alive while she is healing, feed her what ever she will eat.

I'm about 90% sure the other 5 died from coccidiosis. Black blob poops, lethargic, not moving around. This chick was just starting to get sick when a coworker called me to come get her. Was finally able to get some corrid too. Had 2 that didn't respond to the corid but this one is up and moving and eating and drinking and pooping normal. She's going to be quarantined for at least a week.